Wireless communication networks have traditionally functioned to allow general purpose devices such as cellular phones, PDAs, and laptops to transmit and receive information reliably and on demand. Currently, more and more devices with proprietary functions are being designed with internet connectivity in mind. These devices are known as “internet of everything” (IOE) devices. They can include, for example, household appliances, location beacons, or status monitors for remotely located facilities. Some IOE devices are designed to function for very long periods of time—weeks, months, or even years—on a battery, without access to another power source. In these applications there is a need for minimizing the power consumed by radio communications with the IOE device.
Conventional systems employ sleep cycles during which an IOE device's transceivers are powered down to save battery. The IOE device has an internally stored schedule that instructs the device to wake up its transceivers when the device is due to listen for potential data transmissions. Depending on the application, these wake up events can occur as frequently as once every second. However, a given IOE device will often have a data transmission waiting for it as little as 10% or less of the time. While turning transceivers on for a fraction of each second as compared to leaving them on constantly results in significant power savings, such systems are still expending power to run full power transceivers when 90% or more of the time there is no data waiting for them. It is therefore desirable to further economize by reducing the power used by the transceivers in data cycles where no data is transmitted to an IOE device.
In a system that includes IOE devices with low power transceivers, the base station needs to be configured to communicate with the low power transceivers, which may require a different signal configuration than normal power transceivers. In systems containing devices with low power transceivers as well as devices with normal power transceivers, it may become necessary to multiplex the downlink signal between the two types of devices. It is therefore desirable to design a protocol that ensures that the downlink signals can be appropriately received by both types of transceivers.